1. Field of the Invention
The present invention relates to a method, apparatus, and medium for controlling a servo using a detected header field signal in an optical recording and/or reproducing apparatus, and a method, apparatus, and medium controlling the detection of the header field signal. More particularly, the present invention relates to a method, apparatus, and medium for controlling a servo using the header field signal, and a method, apparatus, and medium controlling the detecting of the signal, representing the header field, recorded on a DVD-RAM disc.
2. Description of the Related Art
A digital versatile disc-random access memory (DVD-RAM) disc includes an embossed area, containing an embossed pit sequence, and a recording/reproducing area where data can be recorded in the form of a groove wobble and/or a land wobble. The recording/reproducing area includes a plurality of sectors, each having an embossed header area including a header field. In such a DVD-RAM disc, a signal indicating the presence of the header field may appear in other signal detections. The presence of the header field signal in the tracking error signal adversely affects control of a tracking servo, and similarly adversely affects the counting of the number of tracks, as performed in a seek mode operation of the DVD-RAM disc. Thus, it would be preferential to remove the effects of the header field signal in the tracking error signal.
Unlike operations performed during a reproduction mode operation, in a seek mode operation, which may include search or track jump operations, an optical pickup head jumps tracks, counts the number of tracks jumped, and moves to a target track. Here, it is very important to accurately count the number of tracks. However, in a case of a DVD-RAM, it is difficult to accurately count the number of tracks because of the presence of the header area and the correspondingly inadvertently detected header field.
Further, typically a tracking servo follows a track using a track error signal in the recording/reproducing operation of the DVD-RAM. However, as noted above, the track error signal can be affected by the presence of the header field, resulting in deterioration of the stability of the tracking servo, and ultimately deterioration of a characteristic of a playback signal. As seen in FIG. 1, before the tracking servo is controlled, the track error signal is illustrated as also containing a signal representing the presence of the header field. As shown in FIG. 2, after the tracking servo is controlled, the header continues to affect the track error signal. Thus, it would be preferential to have a method, apparatus, or medium to control the tracking servo to follow the track error signal without being affected by the header field.
In addition, it is noted that in an event that a header identification (ID) is not read and a header field is not properly predicted, due to instability in the system, or if a playback signal detector does not properly detect the header field, in existing optical recording and/or reproducing apparatuses, the stability of servo control becomes deteriorated. It would be preferential to have a method, apparatus, or medium for stable servo control through proper header field detection.